Ink jet recording apparatus

ABSTRACT

An ink jet recording apparatus comprising a counter or timer acting during a nonprinting period while a printing control device is supplied with an electric power; and ink jet system having a pump driving circuit actuated by an output signal delivered from the counter or timer when there is completed a cycle of counting or timing made by said counter or timer, wherein preliminary ejection of ink is effected without normal printing intermittently at the end of each counting or timing cycle.

United States Patent 1 H 1 88 Kashio a Dec. 9, 1975 [541 INK JET 3,488.664 I/I97O Winston i, 346/75 [75] Inventor: Toshio Kashio, Yamato, Japan [73] Assignee: Casio Computed (10., Ltd., Yamaro, Primary Examiner-Joseph We Hartary Japan Attorney, Agent or FirmFlynn & Frishauf [22] Filed: July 3, 1974 [21] Appl. No.2 486,479

57 ABSTRACT Related US. Application Data [63) coml'luaion of 314947 1972- An ink jet recording apparatus comprising a counter abandmed' or timer acting during a nonprinting period while a printing control device is supplied with an electric [30] Foreign Apphcatmn Pnonty Dam power; and ink jet system having a pump driving cir- Decn 1971 Japan 46-l0l444 cuit actuated by an output signal delivered from the counter or timer when there is completed a cycle of US. Cl 346/|40 counting or timing made by said counter or timer, 1 l- H G 11 15/18 wherein preliminary ejection of ink is effected without Fle|d Search 140 normal printing intermittently at the end of each counting or timing cycle. [56] References Cited UNITED STATES PATENTS 4 Claims 2 Drawing Fi 3,136,594 6/l964 Ascoli 346/75 X ELECTRIC SOURCE \10 MAIN CONTROL UNIT PRINTING INSTRUCTIONS i DEFLECTING CIRCUIT WK RECORDING TANK "i PUMP UN|T n 1 i l4 US. Patent Dec. 9, 1975 Sheet 1 of 2 3,925,788

ELECTRIC SOURCE N {Q MAIN CONTROL UNIT PRINTING INSTRUCTIONS I? Is S TIMER DEFLECTING UNIT CIRCUIT INK INK RECORDING TANK PUMP UNIT INK JET RECORDING APPARATUS This is a continuation of application Ser. No. 3l4,947, filed Decv l4, I972 now abandoned.

BACKGROUND OF THE INVENTION This invention relates to an improved ink jet recording apparatus for ejecting ink in fine particles, and controlling the scattering direction of ink particles by a deflection system so as to draw characters or patterns distinctly on a sheet of recording paper.

An ink jet recording apparatus generally ejects ink in fine particles from a nozzle communicating with an ink tank utilizing a strong electric field and scans scattering ink particles by a deflection system including deflection plates in accordance with the character signals supplied to said deflection system, thereby drawing characters or patterns on a sheet of recording paper. In this case, the nozzle for ejecting ink has an extremely fine inner diameter as about O.l mm. Accordingly, during a nonprinting period in which there is not ejected any fresh ink, there occur the drawbacks that the previously supplied ink considerably retreats from the opening of the nozzle or is solidified there. Namely, if, in case said nonprinting period continues long, the recording apparatus is started, th "I about one line of initial printing fails to indicate distinct characters or patterns, because fresh ink can not be freely ejected.

To avoid such drawbacks, it may be contemplated to actuate an ink jet system for about I to 3 seconds when the recording apparatus is supplied with power for start, just before there is received a printing instruction signal, and push fresh ink up to the opening of an ink jet nozzle so as to eliminate lumpy ink previously remaining there. Namely, this process consists in giving a command for preliminary ejection of ink for l to 3 seconds when the recording apparatus is supplied with power and commencing the normal ejection of ink under good condition at the arrival of a printing instructions, thereby effecting the clear printing of characters or patterns corresponding to the character signals received.

However, where such recording apparatus is used as the output device of, for example, an electronic computer or telecommunication means, the apparatus is often left in a state waiting for printing after power supply. If, in case the ejection of ink is attempted for the normal operation of a nozzle after power supply, said waiting period continues long, then the previously supplied ink will considerably retreat from the nozzle tip or will be solidified there, resulting in a failure to carry out good printing upon receipt of printing instructions.

It is accordingly the object of this invention to provide an ink jet recording apparatus which always attains the free ejection of ink upon receipt of a printing command even when said apparatus is long kept in a state waiting for printing after power supply, thereby distinctly drawing or printing characters or patterns.

SUMMARY OF THE INVENTION According to an aspect of this invention, there is pro vided an ink jet recording apparatus which comprises a timer for counting or timing a nonprinting period while a printing control device is supplied with power; an ink ejector actuated for preliminary ejection intermittently each time the count or time at which the timer is set in advance is brought to an end; and a means for deflecting scattering ink particles toward an ink collector when said ink ejector is operated thereby keeping the printing nozzle in a normal ink ejectable condition.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a block circuit diagram of an ink jet recording apparatus according to an embodiment of this invention; and

FIG. 2 shows the circuit arrangement of an inkjet recording apparatus according to another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I, reference numeral 11 represents a main control device for controlling printing, which is actuated when a switch 12 connected to a power source 10 is thrown on. The main control device II so acts as to drive an ink pump 13 which may be a conventional ink pump upon receipt of a printing command, and to deliver ink under pressure from an ink tank I4 to the nozzle of a recording section I5, thereby ejecting ink from the nozzle in fine particles. The con trol device 11 further controls the operation of a deflection circuit 16 by the signals corresponding to characters being printed, causing scattering ink particles ejected from the nozzle to be deflected to a sheet of recording paper for printing of characters or patterns thereon. The switch 12 of the power source 10 is also connected to a timer 17 for its actuation. When the preset time of the timer 17 is brought to an end, said timer 17 gives a command for preliminary ejection of ink to the ink pump 13 and also supplies a control signal to a deflection circuit 16, which in turn generates a deflection signal to conduct ejected ink particles to an ink collector (not shown) disposed outside of the re cording paper. The timer 17 which is operated by the power source 10 is reset to its original state upon re ceipt of a printing command from the main control device 11. The timer I7 is set at a length of time, for example, l5 to 30 minutes shorter than a maximum period in which ink can be normally ejected from the nozzle.

According to the first embodiment of this invention, the recording apparatus is made ready for printing when the power supply switch 12 is thrown in (i.e., turned on). At this time, a signal representing the detection of power supply controls the operation of the ink pump 13 and the deflection circuit 16, causing ink to be preliminarily ejected to an ink collector (not shown) for a short time. Accordingly, the recording apparatus is brought to a state waiting for printing with the nozzle made ready for normal operation. When supplied with a printing command under this condition, the main control device 11 causes the ink pump l3 to be operated for ejection ofink from the nozzle and also the deflection circuit 16 to be so actuated as to effect the printing of characters or patterns on the recording paper according to said printing command. When the power supply switch 12 is thrown in, the timer also commences operation. However, each time the main control device I I is supplied with a printing command, the timer 1? is reset. For example, where there is received a printing command during the 30-minute period at which the timer I7 is set, then there is not generated any output signal from said timer l7, preventing the operation of any part of the recording apparatus resulting from the action of the timer 17.

wants Where there is not received a printing command even 3U minutes after power supply, or upon lapse ol 30 minutes alter the linal printing command is given, then the timer l7 produces an output, causing the ink pump l3 to he tl!l\clt for preliminary ejection of ink, and also the deflection circuit in to he so controlled as to conduct c ected ink particles to an inlt collector (not shown J. when this condition is reached, the timer 17 is brought back to its original state. 'lherclorc, unless there is issued a printing command again for a period ol 30 minutes, then ml; is preliminarily ejected. Namely, said preliminary election is carried out intermittently upon lapse of each fithntinule period. it there is not supplied a printing instruction at that time.

The recording apparatus according to the first ljHl' hodinient effects preliminary ejection oi ink. each time a nonprinting period under power supply condition ex eeeds the preset time oi the timer 1?, therehy preventing the obstruction of normal ejection of ink due to good freely flowing ink being always supplied to the nozzle opening.

FIG. 2 showing a recording apparatus according to another embodiment omits: a ptnver supply circuit. However, there will now he described the second en1 hodirnent on the assumption that there is alvtays sup plied power. Reference numeral 18 denotes a printing output signal buffer register which is stored with signals representing characters or patterns being printed. Said character signals are read out upon receipt of synchrtr nizing pulses generated by a source 1) thereof, and then conducted to a character signal generating regis ter 20 to be stored therein. An output from said eharaeter signal generating register 20 is supplied to a character signal generator 21, which in turn produces charac ter signals. The character signals are conducted to the control circuit 22 of a character composing counter 23. This counter 23 makes counting according to a counting command delivered from the control circuit 22 to indicate the required extent of deflection in the X and Y directions in the form of a digital output.

Where characters or patterns are formed of. a series of dots, character signals stored in the character signal generator 2i are read out by synchronizing signals from the source 19 thereof to indicate the positions of dots constituting characters being printed in the form of digital signals in the X and Y directions. These digital sig nals are converted to analog signals by digital-to-analog converters 24 and Z and supplied to deflection circuits 26 and 27 acting in the X and Y directions respectively The X direction deflection plate 23 and Y direction de t'lcctiort plate 29 of the recording section are irn pressed with deflection voltage by said deflection cir euits 26 and 217W The character signal register Ell produces a com-- mand to generate character signals. These character signals are conducted to a printing control clrtuit 30, which actuates pump driving circuit 31 to drive the ink pump 13, causing ink to he delivered under pres sure from the ink tank 24 to the nozzle 32 ot the re cording section 25. is impressed high voltage by a high voltage generator 35 across the nonle and an ac eeleratiun electrode 34 to direct ink particle ejected from the nozzle 32 to a platen 35 on which there is sup ported a sheet of recording paper. The printing control circuit also gives a. printing C(JlltlOlllflg command to the control circuit 22 oi the character composing counter 23. in the absence ol a printing controlling command. said control circuit 22 actuates an ink col til lector specifying circuit 36, which instructs the Y direetion deflection circuit 27 to deflect ink particles ejected from the nozzle 32 to an ink collector 37 disposed below the platen 35 of the recording section 15. Where the character composing counter 23 generates character signals, the character signal generating register 20 instructs said counter to act as such. In the absence of said instruction, the character composing counter 23 acts as a ring counter. At the end of the preset counting, this ring counter gives a command to the pump driving circuit 31 to operate the pump l3.

According to the recording apparatus of the second embodiment, where the printing output signal buffer register 18 is stored with signals of characters or patterns being printed, said character signals are read out to the character signal generating register 20 by synchronizing signals from the source thereof. Accord ingly, the character signal generator 21 is instructed to generate character signals, thereby actuating the control circuit 22 of the character composing counter 23 as well as the counter 23 itself. Thus the required extent to which ink particles should be deflected for the drawing of characters or patterns is indicated in the form of digital signals, which are conducted to the digi tal-to-analog converting circuits 24 and 25 to he changed into analog signals. Since the recording apparatus of this invention presents characters or patterns in the form of a series ofdots, signals ofcharacters or pat terns stored in the character signal generating register 21) are converted by the character signal generator 21 into signals representing the eo-ordinate positions of dots which are successively read out by the control circuit 22 of the character composing counter 23. Thus the co-ordinate positions of character forming dots are counted in the X and Y directions of the control circuit 22 of the character composing counter 23. The digitalto--analog converting circuits 24 and 25 produce analog signals corresponding to the positions of dots being printed in the X and Y directions, thereby actuating the X direction deflection circuit 26 and Y direction deflection circuit 27 which impress deflection voltage corresponding to the positions of dots constituting characters or patterns on an X direction deflection plate 28 and Y direction deflection plate 29. These deflection plates 28 and 29 acting in the X and Y directions deflect ink particles ejected from the nozzle 32 by the action of the pump driving circuit 31 to the recording paper supported on the platen 35, for the drawing of characters or patterns.

Where the printing output signal buffer register 18 is not stored with any character signal and consequently no printing is carried out, then the character signal gencrating register 20 is neither stored with any character signal. Accordingly. there is not produced any character signal from the character signal generator 21. Since,

under this condition, the printing control circuit 30 does not generate any signal, the control circuit 22 0f the character composing counter 23 actuates the ink collector specifying circuit 36. Where the character signal generating register 20 does not produce any character signal, then the unit elements of the character composing counter 23 disposed in the X and Y directions respectively act as a series of ring counters. Thus the Y direction deflection circuit 27 is impressed with deflection voltage so as to cause ink particles ejected from the nozzle to he deflected to the ink collector 37. At this time the character composing counter 23 now acting as a ring counter advances counts upon receipt of synchronizing signals and actuates the pump driving circuit 31 for l to 3 seconds upon completion of one cycle of counting, causing ink to be preliminarily ejected from the nozzle. Namely, preliminary ejection of ink is intermittently effected from the nozzle 32 to the ink collector 37, each time the counting cycle of the character composing counter 23 is brought to an end.

In other words, the character composing counter 23 acts as a sort of timer in the absence of a printing command. Namely, the character composing counter 23 permits the intermittent preliminary ejection of ink to the ink collector 37 disposed outside of the recording paper, each time the cycle of counting (for example, l5 to 30 minutes) made by the character composing counter 23 now acting as a ring counter is brought to an end.

As described above, the recording apparatus of this invention is characterized in that if, in case the apparatus is kept in a state waiting for printing under a power supply on condition, there arises a relatively long nonprinting period, then preliminary ejection of ink is automatically effected without normal printing, thereby unfailingly preventing ink from considerably retreating from the nozzle opening or being solidified there, a factor most disturbing characters or patterns drawn or printed on the recording paper; and that even where printing is carried out at a relatively long interval, characters or patterns can always be drawn or printed distinctly from the very outset. Therefore, the ink jet recording apparatus of this invention can be effectively used as the output means of computers and telecommunication devices.

What is claimed is:

I. An ink jet recording system comprising:

a source of electric power; and

a recording apparatus selectively coupled to said source of electric power, said recording apparatus including:

a nozzle for emitting ink droplets for printing;

deflecting means including means for deflecting said ink droplets on a recording medium to print characters thereon;

an ink collector for collecting ejected ink droplets which are not used to print characters;

a timing means coupled to said power source for periodically generating an output signal upon the lapse of a predetermined time period when electric power is supplied to said recording apparatus;

a source of print command signals;

ink ejection means coupled to said source of print command signals and to said nozzle for producing a pre-printing ejection of ink droplets from said nozzle for a period of time just prior to the printing of characters and in response to print command signals from said print command signal source, said ink ejection means being further coupled to said timing means for producing a nozzle clearing ejection of ink droplets from said nozzle for a given period of time in response to said periodic output signals from said timing means and independent of said print command signals; and

a deflection control means coupled to said deflecting means and to said timing means for causing said deflection means to deflect said nozzle clearing ejection of ink droplets which are ejected in response to said periodic timing means output signals to said ink collector, thereby maintaining said nozzle in a normal ink ejectable condition over extended periods of time.

2. An ink jet recording system according to claim I comprising a switch coupling said recording apparatus to said source of electric power, said timing means having an input coupled to said switch to activate said timing means upon operation of said switch to couple the electric power to said recording apparatus.

3. An ink jet recording system according to claim 1 comprising means coupling said source of print command signals to said timing means for resetting said timing means responsive to a print command signal, whereby said timing means periodically generates said output signals upon the lapse of said predetermined period of time between print command signals and when said electric power is applied to said recording apparatus.

4. An ink jet recording system according to claim 1 wherein said nozzle clearing ejection is for a substantially longer time duration than said pre-printing ejection.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3,925,788 DATED 1 December 9, 1975 INVENTOR(S) Toshio Kashio It iscertitied that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

On the initial page of the patent, change the name and address of the Assignee to;

Casio Computer Co. Ltd.

Tokyo, Japan.

Signed and Sealed this twentieth Day of April1976 [SEAL] v Arrest.-

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmisslmwr of Parents and Trademarks 

1. An ink jet recording system comprising: a source of electric power; and a recording apparatus selectively coupled to said source of electric power, said recording apparatus including: a nozzle for emitting ink droplets for printing; deflecting means including means for deflecting said ink droplets on a recording medium to print characters thereon; an ink collector for collecting ejected ink droplets which are not used to print characters; a timing means coupled to said power source for periodically generating an output signal upon the lapse of a predetermined time period when electric power is supplied to said recording apparatus; a source of print command signals; ink ejection means coupled to said source of print command signals and to said nozzle for producing a pre-printing ejection of ink droplets from said nozzle for a period of time just prior to the printing of characters and in response to print command signals from said print command signal source, said ink ejection means being further coupled to said timing means for producing a nozzle clearing ejection of ink droplets from said nozzle for a given period of time in response to said periodic output signals from said timing means and independent of said print command signals; and a deflection control means coupled to said deflecting means and to said timing means for causing said deflection means to deflect said nozzle clearing ejection of ink droplets which are ejected in response to said periodic timing means output signals to said ink collector, thereby maintaining said nozzle in a normal ink ejectable condition over extended periods of time.
 2. An ink jet recording system according to claim 1 comprising a switch coupling said recording apparatus to said source of electric power, said timing means having an input coupled to said switch to activate said timing means upon operation of said switch to couple the electric power to said recording apparatus.
 3. An ink jet recording system according to claim 1 comprising means coupling said source of print command signals to said timing means for resetting said timing means responsive to a print command signal, whereby said timing means periodically generates said output signals upon the lapse of said predetermined period of time between print command signals and when said electric power is applied to said recording apparatus.
 4. An ink jet recording system according to claim 1 wherein said nozzle clearing ejection is for a substantially longer time duration than said pre-printing ejection. 